// Object.defineProperty(window,'PI',{
//   value: 3.14,
//   writable: false
// })
// console.log(PI)
// PI = 5
// console.log(PI)

const obj = {
  name: 'xiecheng',
  age:34,
  skill:{
    name:'code',
    year:11
  }
}
console.log(obj)
Object.freeze(obj)  // 冻结obj,只能浅层冻结
obj.school = 'imooc'
obj.skill.year = 12
console.log(obj)

const arr = [1,2,3]
arr.push(4)
console.log(arr)

